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The decarbonylation of transition metal acyl complexes using chlorotris(triphenylphosphine)rhodium(I)
P23
Journal of OrgunometaUic Chemistry Elsevier Sequoia LA., Lausanne
Printed in The Netherlands
PRELIMINARY
COMMUNICATION
THE DECARRONYLATION OF TRANSITION METAL ACYL COMPLEXES USING CHLOROTRIS(TRIPHENYLPHOSPHINE)RHODHJM(I) JOm J. ALEXANDERand ANDREWWOJCICKI TheMcPherson and Evans Chemical Laboratories, The Ohio State UniversiLy. Columbus, Ohio 43210 (IJXA.)
(ReceivedOctober25th, 1968)
In the course of investigations of optically active transition metal complexes1 we became confronted with the problem of decarbonylating Cs Hs Fe(CO)s [COCH(CHs&Hs ] to the corresponding alkyl. Since both thermal and photochemical decarbonylation conditions2 proved too vigorous to avoid decomposition of either the acyl dicarbonyl complex or the secondary alkyl dicarbonyl complex formed, we decided to examine reaction of CsHsFe(C0)2 [COCH(CHs&Hs] with Rh[P(CsHs)s] sC1. Our choice of Rh[P(CGHs)s] sC1 as a potential decarbonylating agent was prompted by recent disclosures3s4that this complex converts aldehydes and acyl halides under mild conditions to the corresponding hydrocarbonand alkyl (aryl) halides and/or olefms, respectively, Rh [P(C, Hs), ] 2 (CO)Cl becoming the rhodium-containing product in each case. The reaction of Cs Hs Fe(C0)2 [COCH(CHs)C6 Hs ] * with Rh[P(C6 Hs )s ] s Cl in dichloromethane at 27” for 3 h, followed by filtration to remove the precipitated Rh [P(&Hs)a ] 2 (CO)Cl (- 75%) and chromatography on alumina of the filtrate, yielded the alkyl Cs H5 Fe(CO)2 CH(CHs)C6 Hs* (54%), some P(&Hs)s, and a trace of the unreacted acyl (eqn. 1). Cs Hs Fe(C0)2 :-?H-Cs Hs 0
f Rh [P(C, Hs )3 ] 3Cl + Cs Hs Fe(CO)2 YH-Ce Hs +
CHs
CH3 WW6H5)312(WC~
+P(C6H5)3
(1)
foregoing experiment suggested further investigations designed @a) to elucidate the scope of the reaction and (b) to ascertain the source of the abstracted CO, whether from the acyl group or from a terminal position of the iron acyl complex. Reported herein are preliminary results of these studies. The complexes Cs Hs Fe(CO), (COR) (R = CHs and CsHs) react with Rh[P(C6H5)3] 3 Cl under similar experimental conditions (CH2 Cl:! or CH2Cls -C6 H6 solvent, 25-30”, 3-S h) to afford the corresponding alkyl and aryl in 40% and 5% yields, respectively. The other isolated metal carbonyl products are Cs Hs Fe&O) [P(C, H5)3] (COR) (R = CH3 and Cc_H5*) (4% and 16%, respectively) and Rh [P(& Hs)3] 2 (CO)C1(88% and lOO%, respectively). Cs Hs Mo(CO)~(COCF~) yields only Cs Hs Mo(CO), [I?(& Hs )s] (COCF3)* The
*A new compound; s&sfactory
chemical analyses have been obtained.
J. OrganometaL Chem.
15 (1968)
P23-P24
PRELIMINARY
p24
COMMUNICATION
(70%) along with Rh[P(C6Hs)3] 2(CO)Cl (100%). No detectable reaction occurred in ca 28 h between Cs H6 Fe(CO)* (COCF3) and Rh [p(C, H5)3] j Cl; Cs Hs Fe(CO)z S(O), R (R = CH3 and CH2 C, Hs ) afford after 5 h virtually quantitative yields of Rh [I?(& Hs )5] z (CO)Cl but no iron carbonyls, suggesting rapid decomposition after abstraction of a terminal CO by the rhodium complex. Insight into the mechanism of the above decarbonylations is obtained upon
examination of the nature of the products from the reaction of Cs H5 Fe(CO)* (’ 3 COCHa) with Rh[P(C, HS)3 ] 3 Cl. The alkyl C5 H5 Fe(CO)(’ 3 CO)CH3 and the acyl were characterized by IR spectroscopy, which also CSHSF~(CO)[PGH&](‘~COCH~) established presence of only the natural abundance of 13C0 in the rhodium carbonyl, Rh [I?&, H5)3] z (CO)Cl. The observed pattern of distribution of ’ 3 CO indicates that a terrnind CO is abstracted from Cs Hs Fe(CO), (13COCH3); the coordinately unsaturated iron monocarbonyl then rearranges via a methyl group migration5 to give
Cs Hs Fe(CO)(13 CO)CH3 or, alternatively, combines with P(CsHs)3 yielding C; iii, Fe(C0) [P(CB HS )3 ] (’ 3 COCH3). The following scheme su mmxizes these results:
,3!CH
“Co
/ Fe-CH3 \
/Fe\
CO
CO p“=d’3~
’ .
We are currently investigating these reactions further with a view to synthesizing alkyl complexes conkining transition metal - secondary and tertiary carbon bonds. ACKNOWLEDGEMENTS
This
investigation
has
been supported by the Petroleum
Research Fund,
administered by the American Chemical Society, and by the National Science Foundation_
J.J.A. thanks The Ohio State University for a Postdoctoral
Fellowship.
REFERENCES
Alexander and A, Wojcicki, in M. Cais (Ed.), Progress in Coordination Chemistry, Elsevier, New York, 1968, p-383-384. RB. King and M.B. Bisnette, J. oIgonome?aL C?zem.. 2 (19649 15. K. Ohno and J. Tsuji, J. Amer. Chem. SOC., 90 (1968) 99. M,C. Baird, C.J. Nyman and G. Wilkinson,J. Chem Sot. A. (1968) 348. K_ Noack and F. CaiderazzoJ 0rganometaL Ci?em., IO (1967) 101.
1 J.J. 2 3 4 5
J. OrganometaL- Chem, 15 (1968) P23-P24
Journal of OrgunometaUic Chemistry Elsevier Sequoia LA., Lausanne
Printed in The Netherlands
PRELIMINARY
COMMUNICATION
THE DECARRONYLATION OF TRANSITION METAL ACYL COMPLEXES USING CHLOROTRIS(TRIPHENYLPHOSPHINE)RHODHJM(I) JOm J. ALEXANDERand ANDREWWOJCICKI TheMcPherson and Evans Chemical Laboratories, The Ohio State UniversiLy. Columbus, Ohio 43210 (IJXA.)
(ReceivedOctober25th, 1968)
In the course of investigations of optically active transition metal complexes1 we became confronted with the problem of decarbonylating Cs Hs Fe(CO)s [COCH(CHs&Hs ] to the corresponding alkyl. Since both thermal and photochemical decarbonylation conditions2 proved too vigorous to avoid decomposition of either the acyl dicarbonyl complex or the secondary alkyl dicarbonyl complex formed, we decided to examine reaction of CsHsFe(C0)2 [COCH(CHs&Hs] with Rh[P(CsHs)s] sC1. Our choice of Rh[P(CGHs)s] sC1 as a potential decarbonylating agent was prompted by recent disclosures3s4that this complex converts aldehydes and acyl halides under mild conditions to the corresponding hydrocarbonand alkyl (aryl) halides and/or olefms, respectively, Rh [P(C, Hs), ] 2 (CO)Cl becoming the rhodium-containing product in each case. The reaction of Cs Hs Fe(C0)2 [COCH(CHs)C6 Hs ] * with Rh[P(C6 Hs )s ] s Cl in dichloromethane at 27” for 3 h, followed by filtration to remove the precipitated Rh [P(&Hs)a ] 2 (CO)Cl (- 75%) and chromatography on alumina of the filtrate, yielded the alkyl Cs H5 Fe(CO)2 CH(CHs)C6 Hs* (54%), some P(&Hs)s, and a trace of the unreacted acyl (eqn. 1). Cs Hs Fe(C0)2 :-?H-Cs Hs 0
f Rh [P(C, Hs )3 ] 3Cl + Cs Hs Fe(CO)2 YH-Ce Hs +
CHs
CH3 WW6H5)312(WC~
+P(C6H5)3
(1)
foregoing experiment suggested further investigations designed @a) to elucidate the scope of the reaction and (b) to ascertain the source of the abstracted CO, whether from the acyl group or from a terminal position of the iron acyl complex. Reported herein are preliminary results of these studies. The complexes Cs Hs Fe(CO), (COR) (R = CHs and CsHs) react with Rh[P(C6H5)3] 3 Cl under similar experimental conditions (CH2 Cl:! or CH2Cls -C6 H6 solvent, 25-30”, 3-S h) to afford the corresponding alkyl and aryl in 40% and 5% yields, respectively. The other isolated metal carbonyl products are Cs Hs Fe&O) [P(C, H5)3] (COR) (R = CH3 and Cc_H5*) (4% and 16%, respectively) and Rh [P(& Hs)3] 2 (CO)C1(88% and lOO%, respectively). Cs Hs Mo(CO)~(COCF~) yields only Cs Hs Mo(CO), [I?(& Hs )s] (COCF3)* The
*A new compound; s&sfactory
chemical analyses have been obtained.
J. OrganometaL Chem.
15 (1968)
P23-P24
PRELIMINARY
p24
COMMUNICATION
(70%) along with Rh[P(C6Hs)3] 2(CO)Cl (100%). No detectable reaction occurred in ca 28 h between Cs H6 Fe(CO)* (COCF3) and Rh [p(C, H5)3] j Cl; Cs Hs Fe(CO)z S(O), R (R = CH3 and CH2 C, Hs ) afford after 5 h virtually quantitative yields of Rh [I?(& Hs )5] z (CO)Cl but no iron carbonyls, suggesting rapid decomposition after abstraction of a terminal CO by the rhodium complex. Insight into the mechanism of the above decarbonylations is obtained upon
examination of the nature of the products from the reaction of Cs H5 Fe(CO)* (’ 3 COCHa) with Rh[P(C, HS)3 ] 3 Cl. The alkyl C5 H5 Fe(CO)(’ 3 CO)CH3 and the acyl were characterized by IR spectroscopy, which also CSHSF~(CO)[PGH&](‘~COCH~) established presence of only the natural abundance of 13C0 in the rhodium carbonyl, Rh [I?&, H5)3] z (CO)Cl. The observed pattern of distribution of ’ 3 CO indicates that a terrnind CO is abstracted from Cs Hs Fe(CO), (13COCH3); the coordinately unsaturated iron monocarbonyl then rearranges via a methyl group migration5 to give
Cs Hs Fe(CO)(13 CO)CH3 or, alternatively, combines with P(CsHs)3 yielding C; iii, Fe(C0) [P(CB HS )3 ] (’ 3 COCH3). The following scheme su mmxizes these results:
,3!CH
“Co
/ Fe-CH3 \
/Fe\
CO
CO p“=d’3~
’ .
We are currently investigating these reactions further with a view to synthesizing alkyl complexes conkining transition metal - secondary and tertiary carbon bonds. ACKNOWLEDGEMENTS
This
investigation
has
been supported by the Petroleum
Research Fund,
administered by the American Chemical Society, and by the National Science Foundation_
J.J.A. thanks The Ohio State University for a Postdoctoral
Fellowship.
REFERENCES
Alexander and A, Wojcicki, in M. Cais (Ed.), Progress in Coordination Chemistry, Elsevier, New York, 1968, p-383-384. RB. King and M.B. Bisnette, J. oIgonome?aL C?zem.. 2 (19649 15. K. Ohno and J. Tsuji, J. Amer. Chem. SOC., 90 (1968) 99. M,C. Baird, C.J. Nyman and G. Wilkinson,J. Chem Sot. A. (1968) 348. K_ Noack and F. CaiderazzoJ 0rganometaL Ci?em., IO (1967) 101.
1 J.J. 2 3 4 5
J. OrganometaL- Chem, 15 (1968) P23-P24